In many oil and/or gas producing wells, it is essential to measure parameters such as pressure and temperature at different points in the wellbore for safety, efficiency and production reasons. Typically, as shown in FIG. 1, in the past and in particular within various deviated wells that may have both vertical and horizontal sections, this has been achieved in a well casing 1 by installing a lower sensor 2 deployed at the end of a cable 3 to a depth near the toe 4 of the wellbore inside a tubing string 5. In the past, in a typical scenario, an upper sensor 6 and cable 7 are clamped or banded onto the outside of a production tubing string 8 near the heel 9 of the wellbore.
During well servicing and other interventions that may be necessary throughout the life of a well, the production tubing string is often pulled out and re-installed at various times, which requires the upper sensor 6 and cable 7 that have been clamped to the outside of the production tubing string to be handled. Handling the sensor and cable adds to the complexity of each intervention and increases the time, costs, and the number of services involved in the intervention. Furthermore there is also a risk of damaging the sensor and cable during deployment and pulling of the production tubing string each time it is handled.
Moreover, by having the sensor and cable attached to the production tubing string, vibrations in the production tubing string created by pumps and other equipment can damage the sensor, resulting in inaccurate readings and/or the need to repair or replace the sensor.
A review of the prior art reveals several systems for measuring pressure in a wellbore. For example, U.S. Pat. No. 8,230,917 teaches a system and method for determining fluid invasion in reservoir zones using a sensor in coiled tubing. US 2004/0031319 teaches a system that displaces a predetermined fluid in order to measure pressure in a highly deviated or horizontal wellbore. US 2011/0229071 teaches a sensor system for taking measurements at a variety of locations in a wellbore using an optical fiber having a plurality of pressure sensors spaced apart on the optical fiber. US 2013/0048380 teaches a method for estimating one or more interval densities in a wellbore by acquiring first and second axially spaced pressure measurements in the wellbore using a tool string containing a number of spaced apart pressure sensors. U.S. Pat. No. 6,116,085 teaches a tubing string housing a plurality of pressure sensor assemblies connected to ports along the tubing string and a plurality of thermocouples operative to measure temperature at points along the tubing string in a wellbore.
In view of the foregoing, there is a need for an apparatus and method for deploying and installing instrumentation into a wellbore wherein subsequent handling of the instrumentation is minimized. There is also a need for an apparatus and method for deploying instrumentation to reduce vibrations on the instrumentation caused by pumps. There is a further need for an apparatus and method for deploying two or more instruments inside of a single tubing string, separate from the production tubing string, wherein measurements can be taken simultaneously at more than one location in the wellbore. There is also a need for such an apparatus and method to enable the monitoring of well conditions at more than one location in the wellbore that is simple to install.